Combined skewer and thermometer



Aug. 11, 1959 E. M. DIGHT COMBINED SKEWER AND THERMOMETER Fild July 6, 1956 a 4 I v! EVELYN M.- DIGHT INVENTOR.

United States Patent 2,398,845 Cowman SKEWER AND THERMOMETER Evelyn M. Dight, Seattle, Wash.

Application July 6, 1956, Serial No. 596,207

1 Claim. 01. 99-421 The present invention relates to the general art of meat cooking devices, and more particularly to a combined skewer and thermometer for use in supporting a roast as it is revolved before a source of heat and with interior means for sensing the interior temperature of the roast, so that its cooking condition will be under observation at a convenient distance at all times.

It is a well established principle that the interior temperature of a roast of meat indicates very accurately the degree to which the interior portion of the roast has been cooked. This varies somewhat with the type of meat.v Considering a roast of beef, for instance, an interior temperature of 170 indicates a well done roast; a temperature of 160 a medium done roast, in which there will be considerable pink meat; and a temperature of 140 indicates a rare roast, yet one that has been cooked to a degree so that the enzyme action has been arrested.

Heat-registering devices based upon this principle have been available for insertion in roasts and have been used for many years. They work exceedingly well with a roast, for instance, that is being cooked in a conventional 1 oven, in that the heat-sensing portion of the thermometer may be inserted substantially in the center of the roast, and the temperature-indicating portion, whether it is a metallic sensing unit or a mercury column unit, can

have the reading portion or reading dial well out of the roast so that it can be easily inspected. In more recent years, however, there has been a marked development in outdoor cooking equipment to meet the increasing demand of persons who may wish to entertain on a rather informal basis and make use of their garden areas, patios and the like. In order to cook meat under these conditions, various arrangements are resorted to; however, there is a particular interest in the so-called charcoal broiling over an open fire or, in some instances, infront of a vertically disposed coal bed. Under these conditions it is very diflicult to determine the interior condition of a roast, because ordinarily a skewer is placed through the roast, and this must be substantial enough to support the roast in a revolving manner, and then it becomes difi'icult to use any of the normal heat sensing devices because of the mass of the interior skewer which is normally at the position of balance or the center of mass, and this is where the sensing unit should be disposed. Further, the metal skewer is an excellent heat conductor and would give false values to a thermometer. It is increasingly desirable to have a visual indication of the degree of cooking of the meat, because wind conditions and many other ambient air circumstances greatly complicate the cooking problem, as against a conventional oven, for in stance, or an interior grill where there are no cold air currents and the like.

In my present invention I have provided a combination between a substantially constructed skewer of a type that will adequately support a roast in a desirable revolving arrangement and at the same time will have centrally disposed therein a heat-sensing device, which may be a mercury column thermometer but, more preferably, a metallic thermometer heat-sensing unit. Means are provided to conduct the temperature reading to a point well away from the heat zone, where it can be easily read. It is therefore believed that I have provided amarked contribution in the art of meat cooking devices.

The principal object of my present invention therefore is to provide a substantially constructed meat skewer;

of a type that may be supported between spaced bearings and revolved by power or manual means, and will have an interiorly disposed heat-sensing unit which may be placed at the center of the roast and the interior temperature be indicated on devices well removed from the heat zone.

A further object of this invention is to provide a combined roast-supporting skewer and meat thermometer which is simple to use and readily adapted to a wide range of meat cooking devices.

A further object of this invention is to provide a combined roast-supporting skewer and meat thermometer in Which the heat-sensing element may be conveniently and accurately centered in the center or mass of the roast,

Further objects, advantages and capabilities will be apparent from the description and disclosure in the drawings, or may be comprehended or are inherent in the de vice. t

In the drawings:

Figure l is a perspective view, partly in section, illustrating one preferred form of my invention.

Figure 2 is an elevational view, partly in section, of a conventional rotisserie motor and reduction gearingunit, illustrating the manner in which driving and supporting connection is made between my meat skewer and this drive means.

Figure 3 is an elevational view, partly in section, illustrating a convenient means for supporting the temperature-indicating end of my device and further illustrating the manner in which a roast may be centered on the heatsensing element.

Figure 4 is an elevational view, partly in section, illustrating the manner in which my skewer is releasably engaged by the driving means also illustrated in Figure 2.

Figure 5 is a perspective view illustrating one form of meat cooking equipment with which this invention is adapted for use.

Referring more particularly to the disclosure in the drawings, the numeral 10 designates a tubular member extending substantially the full length of my meat-supporting skewer. This tube is made preferably of non-corrosive material, of which an excellent example is the present variety of stainless steel available on the market. The tubing should be selected with a Wall thickness that is as thin as will adequately support the largest roast that would normally be mounted on this device, in such a manner that the tube will not bend at its mid-point and thus be difficult to revolve in the normal manner. V

Disposed substantially at the mid-point of tube 10 is the heat-sensing element 12. It is recognized that there are many types of heat-sensing devices that will be operable in this arrangement. However, the preferred form is the type of heat-sensing device which is coiled in a loose coil and arranged so that, as the tem; perature changes, each turn of the coil in its elongation tends to revolve the coil. This coil is harnessed to the present requirement by being fixedly secured as at 14 to an insert member 16, which in turn is locked against rotative or longitudinal movement by a suitable screw 18. With one end anchored, coil 12 will devote its energy to the rotation of the opposite end as 20. Coil end 20 is fixedly secured to a rotatable rod 22, which is led up to and engaged with needle 24 of gauge 26 so that, as coil 12 revolves under changes of temperature,

Patented Aug. 11, 19 59 needle 24' will be revolved and will indicate the actual temperature at the sensing element. The actual temperature may be conveniently read on either of scales 27 or 29. In this connection it is desirable to so install can 12 that rises in temperature tend to tighten the coil and reduce its outside diameter. It is further desirable to select an outside diameter for coil 12 which is a loose fit in the interior of tube 10, to the end' that it will be free to respond, without frictional drag, to changes in temperature, yet will be. to a degree supported by the tube in order that it may be easily harnessed to rotate shaft 22.

Referring to Figure 1, it will be noted that shaft 22 has the one portion 21 which engages coil, 12 and a second portion as 23 with a joining or coupling member between portions 21 and 23 as the non-metallic, insulating unit 25. One purpose of this is to make a break in the heat transfer that might tend to follow along shaft 22 to coil 12 and improperly influence the readings of thermometer 26'. It should be understood that that optimum condition maintains when the heating is largely centered in the portion of the tube immediately surrounding coil 12 and that all reasonable steps be taken to insulate the balance of the tube so that the relatively large area of the skewer will not become an efficient radiating surface which would seriously aflect the accuracy of the readings under varied conditions of the ambient air. To this end insulating tubes 30 and 32 have been provided at the gauge or thermometer dial end of the tube, and at the oppositeend an insulating tube 34 is provided, which should engage the inner wall oftube in the same manner that tubes 30 and 32 engage. This arrangement tends to dampen or limit the How of heat along tube 10 and localize the heat within the heat-sensing portion covering element 12. It is to be further noted that the outer surface of tube 10, following the teachings of heat transfer, should preferably be polished, and this is easily achieved ifthe tube is made of stainless steel or the bright non-ferrous metal tubes. e

' It is of course necessary that the skewer element 10 be provided with a pointed end as 36', so that it will be relatively easy to pass the fairly large diameter skewer through a roast. Point 36 is preferably multisided, as indicated in Figure 1', and is secured to tube l0-as by one or more screws 38; .The multi-faced point 3.6 is the preferred point of attachment of power to revolve the skewer, and this arrangement is illustrated in Figures 2 and 4, in which it will be noted that point 36 is engaged by a complementary socket 40 formed, within the coupling member 42. This coupling member is provided with a large ""asaaew r actual thrust collar portions 56 and 57 are opened and disengaged from groove 44 and permit the insertion or removal of the skewer element. This thrust unit is normally an attachment having the mounting plate 60 and pedestal arrangement 62, which may be readily adapted to various types of motor units M.

The opposite end of the skewer member is revolvably supported by a pedestal-bearing arrangement shown in Figures 3 and. 5. This, bearing member 64 is normally provided with a U-shaped' bearing, open at the top, as will be noted, at 66,. to the end that the skewer can be easily removed from the. unit as soon as the thrust collar elements 56 and 57 are disengaged. Due to the slow I rotative speed of the, skewer element, bearings of a simple order are definitely indicated.

Illustrated in Figures 1 and 3 are a plurality of graduations 70 having a central index or zero at 72. These are to assist in the most favorable positioning of the and the cook may be assured that element 12 is acenough hub portion to accept the driving point 36 and at the same time means are employed tocouple, in rotative arrangement, the coupling member to the output of the reduction gearing which is normally a part of" the motive unit M. In order to overcome the normal thrust, which would be present with any conical or pyramidal engaging surface, as is presented by point 36, I have provided anannular groove as 44 immediately adjacent the point, and this annular groove is normally engaged by the tong-like thrust members, probably best illustrated in Figure 4. These members, consisting of portions 46 and 48., are pivotally secured togetherat 50 and arranged so that, as the handles 52 and 53 are squeezed together against the compression spring 55, the

curately centered in the roast. Conventional anchoring forks as 74- may be employed to secure the roast R in place and also to impart the rotative effort of motor M.

It is believed that it will be clearly apparent from the above description and the disclosure in the drawings that the invention comprehends a novel construction of combined skewer and thermometer.

Having thus disclaimed the invention, I claim:

A combination skewer and thermometer, comprising: a tubular skewer adapted to revolvably support a meat roast; a point, secured in one end of said tubular skewer and providing torque transfer surfaces and an annular groove at the end of said tubular skewer adapted to accept thrust means; a power unit for revolving said skewer;

means for coupling said skewer to. said power means;

thrust means adapted, to seat in said annular groove and position said point in respect to said coupling means; said thrust means comprising two members, each having a thrust collar portion, forming tongs pivoted on a fixed pivot, spring means disposed to close the tongs and stop means limiting the amount of closure to prevent grip.- ping the skewer; temperature-indicating means secured to the opposite end of said skewer; temperature-sensing means disposed in said tubular skewer intermediate its ends; means for, operatively connecting said sensing means and said indicating means; bearings for revolvably sup,- porting said skewer adjacent its opposite ends; and in,- sulation disposed in each end of said tubular skewer, substantially covering the interior of said skewer except for the portion occupied by the. heat-sensing unit, and in contact with the inner wall thereof.

References Cited in the file of this patent UNITED STATES PATENTS 

